Caster wheel braking systems

ABSTRACT

A caster wheel braking system for braking rotation of a caster wheel includes a caster having a caster plate, a horn base coupled with the caster plate and rotatable about a vertical axis, a pair of legs extending downwardly from the horn base, and at least one caster wheel coupled with the pair of legs and rotatable about a horizontal axis defined by a wheel axle. A mounting plate is spaced from the caster by a spacer. A movable plunger is disposed between the caster plate and the mounting plate and is horizontally movable through a slot provided in the spacer. A brake shoe is vertically movable by the movable plunger between a non-braking position in which the at least one caster wheel is permitted to rotate and a braking position in which the brake shoe exerts a braking force on the at least one caster wheel to at least partially hinder rotation of the at least one caster wheel. A pin may be coupled with the movable plunger and be configured to convert horizontal movement of the movable plunger to vertical movement of the brake shoe. Additionally, a biasing element may be provided adjacent to the brake shoe and be configured to bias the brake shoe toward the non-braking position or the braking position. One or more of the caster wheel braking systems may be provided on a transport vehicle configured to move along a ground surface.

TECHNICAL FIELD

The present invention relates generally to casters. More particularly,the invention relates to systems for braking the rotation of a casterwheel.

BACKGROUND

Casters are commonly attached to transport vehicles, such as carts,trailers, trucks, or dollies, and allow for rolling movement of thetransport vehicle along a ground surface. Casters generally include ahorn, also referred to as a yoke, having a pair of legs that extenddownwardly and support a caster wheel that rolls along the groundsurface. Casters may be classified as light-duty or heavy-duty,stem-style or plate-style, swivel or rigid, and kingpin or kingpinless,for example.

A caster is considered light-duty or heavy-duty depending generally onthe magnitude of the load it is designed to support with a caster wheel.Caster wheels come in a large variety of sizes, measured both by thewidth of the wheel tread and by its diameter. Heavy-duty casters aregenerally fitted with larger diameter wheels and wider tread widths thanlighter duty casters. Household furniture normally features lighter dutycasters, with smaller and narrower wheels. In industrial applications,vehicles designed for transporting heavy loads feature heavy-dutycasters with wider and larger diameter wheels.

Casters are generally attached to the support vehicle by either a stemor a mounting plate. Stem casters include a vertical stem, or stud, thatextends upwardly from the horn and is configured to attach the caster toa vehicle. The stem is inserted into a hole or channel provided on thevehicle, such as an office chair or other furniture. In contrast, platecasters include a caster mounting plate for attaching the caster to asurface, such as a bottom surface, of the transport vehicle. Platecasters are generally used for heavy-duty applications, while stemcasters are more common for light-duty applications.

Casters may be permitted to rotate about their vertical axis (termed“swivel”), or they may be fixed or restricted (termed “rigid”). Swivelcasters include a horn base that is rotatably coupled with the castermounting plate or stem such that the horn and caster wheel, comprisingthe lower portion of a mounted caster, may swivel about the verticalaxis relative to the caster mounting plate or stem. This swivelingaction allows for multi-directional rolling movement, including steeringor turning of the transport vehicle. In contrast, rigid casters includea horn that is rigidly attached to the caster mounting plate, such thatthe horn and swivel caster wheel are fixed relative to the castermounting plate and do not rotate about the vertical axis. Transportvehicles may be fitted with one or more swivel casters and one or morerigid casters depending on the application and transport design.

Swivel casters are generally of two designs: kingpin and kingpinless.Kingpin casters are the more traditional design and include a threadedstud or bolt, referred to as a kingpin, which extends downwardly fromthe caster mounting plate and is insertable into a concentric holeprovided on the caster horn. A nut is threaded onto the kingpin and istightened to couple the horn to the caster mounting plate with one ormore bearings between the plate and horn to allow for swivelingmovement. Swivel resistance is dependent on design and fit of matingparts, bearing types, and sometimes the tightness of the nut.Kingpinless casters essentially feature a much larger diameter kingpin,and the major parts are secured by ball bearings which also permit therotational action. The larger kingpin in the kingpinless design providesaccess to the top of the caster wheel through the center of the castermounting plate, made possible by the absence of a vertical stud or boltwithin the caster structure.

Transport vehicles often include swivel casters for maneuverability, forexample for steering and turning the vehicle. Most transport vehicleshaving mounted casters include swivel casters on the operator-end of thevehicle, which is the vehicle end on which the operator pushes or pullsto move the vehicle. This operator-end generally also features a handleon which the operator may exert a pushing or pulling force for movingthe vehicle. A common caster arrangement for a transport vehiclefeatures swivel casters provided on the operator-end of the vehiclehaving the handle, and rigid casters provided on the vehicle endopposite the operator-end. For maximum maneuverability, a vehicle mayhave only swivel casters. An example of this is a common furnituredolly. Such an arrangement provides the advantage of easymaneuverability in tight spaces. However, this arrangement presents adrawback of making consistent directional control difficult along along, straight path. To provide both tight space maneuverability andeasy directional control along longer paths, swivel casters included onthe vehicle may be equipped with swivel locks. Swivel locks may beengaged to prevent the caster from swiveling, thereby allowing theswivel caster to function as a rigid caster. Swivel locks may bedisengaged to allow swiveling when maximum maneuverability is desired.

During use of the transport vehicle it is often desirable to brakerotation of the caster wheels, including those of any swivel casters.For example, during vehicle loading or unloading, or when parked, theoperator may desire that the transport vehicle remain stationary.Accordingly, a caster may incorporate a braking system which may beengaged to apply a braking force to the caster wheel that prevents orsignificantly hinders rotation of the caster wheel depending on anyexternal forces acting against the braking force, such as a horizontalpushing or pulling force on the vehicle. Traditional braking systemsinclude a brake actuating lever or handle which may be moved by theoperator's foot or hand to engage the brake. On swivel casters, thelever or handle is traditionally mounted to the rotatable horn and thusswivels with the horn relative to the caster mounting plate. In use, thehorn may swivel to a position in which the brake actuating lever orhandle is positioned beneath the vehicle or otherwise beyond theconvenient reach of the operator. To engage the brake, the operator mustthen manually position the caster to reach the brake lever or handle, oradjust the vehicle to accomplish this. This activity is bothinconvenient and ergonomically challenging for the operator, who may bebending over to reach the lever while simultaneously attempting tosteady the vehicle or secure the load.

Accordingly, there is a need for a caster wheel braking system thataddresses the challenges and drawbacks associated with swivel casters aspresented above.

SUMMARY

An exemplary embodiment of a caster wheel braking system for brakingrotation of a caster wheel includes a caster having a caster plate, ahorn base coupled with the caster plate and rotatable about a verticalaxis, a pair of legs extending downwardly from the horn base, and atleast one caster wheel coupled with the pair of legs and rotatable abouta horizontal axis defined by a wheel axle. An upper mounting plate isspaced from the caster by a spacer. A movable plunger is disposedbetween the caster plate and the upper mounting plate and ishorizontally movable through a slot provided in the spacer. A brake shoeis vertically movable by the movable plunger between a non-brakingposition in which the at least one caster wheel is permitted to rotateand a braking position in which the brake shoe exerts a braking force onthe at least one caster wheel to at least partially hinder rotation ofthe at least one caster wheel. A pin is coupled with the movable plungerand is configured to convert horizontal movement of the movable plungerto vertical movement of the brake shoe.

Another embodiment of a caster wheel braking system for braking rotationof a caster wheel includes a caster having a caster plate, a horn basecoupled with the caster plate and rotatable about a vertical axis, apair of legs extending downwardly from the horn base, and at least onecaster wheel coupled with the pair of legs and rotatable about ahorizontal axis defined by a caster wheel axle. A mounting plate isspaced from the caster by a spacer. A movable plunger is disposedbetween the caster plate and the mounting plate and is horizontallymovable through a slot provided in the spacer. A brake shoe isvertically movable by the movable plunger between a non-braking positionin which the at least one caster wheel is permitted to rotate and abraking position in which the brake shoe exerts a braking force on theat least one caster wheel to at least partially hinder rotation of theat least one caster wheel. A biasing element is adjacent to the brakeshoe and is configured to bias the brake shoe toward the non-brakingposition or the braking position.

An exemplary embodiment of a transport vehicle configured to move alonga ground surface includes at least one caster wheel braking system forbraking rotation of a caster wheel. The at least one caster wheelbraking system includes a caster coupled with the transport vehicle andhaving a caster plate, a horn base coupled with the caster plate androtatable about a vertical axis, a pair of legs extending downwardlyfrom the horn base, and at least one caster wheel coupled with the pairof legs and rotatable about a horizontal axis defined by a caster wheelaxle. A mounting plate is spaced from the caster by a spacer. A movableplunger is disposed between the caster plate and the mounting plate andis horizontally movable through a slot provided in the spacer. A brakeshoe is vertically movable by the movable plunger between a non-brakingposition in which the at least one caster wheel is permitted to rotateand a braking position in which the brake shoe exerts a braking force onthe at least one caster wheel to at least partially hinder rotation ofthe at least one caster wheel. A pin is coupled with the movable plungerand is configured to convert horizontal movement of the plunger tovertical movement of the brake shoe.

Various additional features and advantages of the invention will becomemore apparent to those of ordinary skill in the art upon review of thefollowing detailed description of the illustrative embodiments taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention and,together with a general description of the invention given above, andthe detailed description of the embodiments given below, serve toexplain the principles of the invention.

FIG. 1 is an isometric view of a transport vehicle having four casters,wherein two of the casters incorporate a caster wheel braking system forbraking rotation of a caster wheel according to one embodiment of theinvention in which an actuator includes a brake lever.

FIG. 1A is an isometric view of a transport vehicle having six casters,wherein two of the casters incorporate the caster wheel braking systemshown in FIG. 1 in which the actuator includes a brake lever.

FIG. 2 is an isometric view of the braking system shown in FIG. 1 inwhich the actuator includes a brake lever.

FIG. 2A is an isometric view of the braking system of FIG. 2, whereinthe caster includes dual caster wheels.

FIG. 3 is a partially disassembled view of the braking system of FIG. 2.

FIG. 4 is a top elevational view of the braking system of FIG. 2, withan upper mounting plate hidden, showing the brake lever in a first brakelever position.

FIG. 4A is a side cross-sectional view of the braking system of FIG. 4,taken along section line 4A-4A, showing a brake shoe in a retracted,non-braking position when the brake lever is in a first brake leverposition.

FIG. 5 is a top elevational view of the braking system of FIG. 2, withthe upper mounting plate hidden, showing the brake lever in a secondbrake lever position.

FIG. 5A is a side cross-sectional view of the braking system of FIG. 5,taken along section line 5A-5A, showing the brake shoe in an extended,braking position when the brake lever is in the second brake leverposition.

FIG. 6 is an isometric view of the braking system of FIG. 2 in which thecaster is provided with a swivel lock, the swivel lock being shown in alocked position.

FIG. 6A is top elevational view of the caster of FIG. 6, taken alongsection line 6A-6A, showing the swivel lock in the locked position.

FIG. 7 is an isometric view of the braking system of FIG. 6, showing theswivel lock in an unlocked position.

FIG. 7A is a top elevational view of the caster of FIG. 7, taken alongsection line 7A-7A, showing the swivel lock in the unlocked position.

FIG. 8 is an isometric view of a transport vehicle having four casters,wherein two of the casters incorporate a caster wheel braking system forbraking rotation of a caster wheel according to another embodiment ofthe invention in which the actuator includes a control cable and a handlever.

FIG. 9 is an isometric view of the braking system shown in FIG. 8 inwhich the actuator includes a control cable and a hand lever.

FIG. 10 is a partially disassembled view of the braking system of FIG.9.

FIG. 11 is a top elevational view of the braking system of FIG. 9, withan upper mounting plate hidden, showing the control cable in a firstcable position.

FIG. 11A is a cross-sectional view of the braking system of FIG. 11,taken along section line 11A-11A, showing the brake shoe in theextended, braking position when the control cable is in a first cableposition and the hand lever is in a first hand lever position.

FIG. 12 is a top elevational view of the braking system of FIG. 9, withthe upper mounting plate hidden, showing the control cable in a secondcable position.

FIG. 12A is a cross-sectional view of the braking system of FIG. 12,taken along section line 12A-12A, showing the brake shoe in theretracted, non-braking position when the control cable is in a secondcable position and the hand lever is in a second hand lever position.

DETAILED DESCRIPTION

Referring to the figures, and beginning with FIG. 1, a transport vehicleis shown in the form of a platform truck or cart 10 having a front end12, a rear end 14, a platform 16, and a transport bar 18. The truck orcart 10 is provided at its front end 12 with a pair of rigid casters andat its rear end 14 with a pair of swivel casters, with one of the rigidcasters being hidden from view. Each of the swivel casters incorporatesan exemplary caster wheel braking system 20 for braking rotation of acaster wheel. The platform 16 is configured to receive a load of one ormore objects for transportation by the vehicle. The transport bar 18, asshown, may be in the form of a pipe handle and an operator may exert apushing or pulling force thereon for moving the vehicle in a desireddirection.

While the transport vehicle is shown in the form of platform truck orcart 10 having four casters, the vehicle may be any other suitabletransport vehicle configured to include casters for providing rollingmovement along a ground surface. For example, FIG. 1A shows a transportvehicle in the form of platform truck or cart 11 having six casters. Thefront end 12 and rear end 14 of the truck or cart 11 each include twoswivel casters, one being hidden from view. A middle portion 13 of thevehicle includes two rigid casters, one being hidden from view.

Although FIGS. 1 and 1A illustrate vehicles 10, 11 having only twoswivel casters incorporating the caster wheel braking system 20, ineither embodiment shown all of the casters disposed at the front end 12and rear end 14 of the vehicles 10, 11 may incorporate the caster wheelbraking system 20, or any other caster wheel braking system describedherein.

Referring to FIGS. 2 and 3, an exemplary embodiment of the brakingsystem 20 includes a caster 22, shown and described herein as aheavy-duty, kingpinless, swivel caster. Persons skilled in the art willappreciate that the caster wheel braking systems disclosed herein may beadapted for other style casters as well.

The caster 22 includes a caster plate 24 and a horn 26, also referred toas a yoke, having a horn base 28 that is rotatably coupled with thecaster plate 24 such that the horn 26 may swivel relative to the casterplate 24 about a vertically oriented central axis A. The caster 22 isprovided with a load bearing (not shown) which operates to enable theswiveling movement. The load bearing may include an outer bearing ringdefined by or formed with the horn base 28 and having an outer ballracefacing radially inward, an inner bearing ring formed with a lowersurface of the caster plate 24 and having an inner ballrace facingradially outward, and a plurality of movable bearing balls disposedbetween the inner ballrace and the outer ballrace.

The horn 26 further includes a pair of legs 30 that are securelyattached, for example by welds, to the horn base 28. The legs 30 extenddownwardly from the horn base 28 and the caster plate 24, and the legs30 include a pair of opposed axle holes 32 for supporting a wheel axle34 and caster wheel 36. The caster wheel 36 is rotatably coupled withthe wheel axle 34 such that it may rotate about the wheel axle 34 topermit rolling movement of the caster 22 and the transport vehicle towhich it is attached. The caster wheel 36 may be of any size, shape, andmaterial suitable for the application and the environment in which thecaster 22 is operated. Suitable materials for the wheel 36 may includeany metals or polymers of varying hardness, including plastics,polyurethanes, and rubbers. For example, the wheel 36 may include a castiron center portion and a polyurethane tread applied to the outercircumference of the center portion. Additionally, the caster 22 ofbraking system 20, or of any other braking system disclosed herein, maybe provided with multiple caster wheels. For example, as shown in FIG.2A, the caster 22 may be provided with dual caster wheels 36 a and 36 bin a side-by-side, parallel arrangement. Like the single caster wheel36, the dual caster wheels 36 a, 36 b may be of any size, shape, andmaterial suitable for the application and the environment in which thecaster 22 is operated.

In addition to the caster 22, the braking system 20 shown in FIGS. 2 and3 further includes an upper mounting plate 40 that is disposedvertically above and substantially parallel to the caster plate 24. Theupper mounting plate 40 and caster plate 24 are spaced apart in avertical direction by a spacer 42, the structural details of which arediscussed below. The caster plate 24, spacer 42, and upper mountingplate 40 are coupled together by any suitable mechanical means, such asby threaded screws, weldment, or integral formation through machining orforging. For example, as shown, threaded screws 46 may be inserteddownwardly through through-holes 39 and 41 provided in the uppermounting plate 40 and in the spacer 42 respectively, and into threadedholes 25 provided in the caster plate 24. The through-holes 39 providedin the upper mounting plate 40 may include countersinks to facilitateinsertion of the screws 46 during assembly and allow the heads of screws46 to lie flush with a top surface of the upper mounting plate 40. Eachthreaded hole 25 in the caster plate 24 is coaxially aligned with thecorresponding through-holes 39, 41 in the spacer 42 and the uppermounting plate 40. Additionally, each threaded hole 25 preferablyextends only partially through a thickness of the caster plate 24, suchthat the screw 46 inserted therein is prevented from extending fullythrough the thickness of the caster plate 24.

The caster plate 24 and/or upper mounting plate 40 may include aplurality of mounting slots 48 for mounting the caster 22 to a transportvehicle. Each mounting slot 48 is preferably configured to receive abolt or other mechanical fastener (not shown) therethrough for securingthe caster 22 to the transport vehicle. In other embodiments, themounting slots 48 may be omitted from either or both of the caster plate24 and upper mounting plate 40. For example, the caster 22 may be weldedonto the transport vehicle, in which case mounting slots may not benecessary and thus not included on either of the caster plate 24 or theupper mounting plate 40.

The braking system 20 further includes an actuator in the form of ahorizontally oriented brake lever 50, which may have grips 52. The grips52 are configured to slip over the ends of the brake lever 50 andprovide a frictional surface to thereby improve the ability of anoperator to grip and manipulate the brake lever 50 with a foot or hand.The grips 52 may be of any ergonomic design and of any suitablematerial, such as rubber or plastic. If desired, the grips 52 may beomitted from the brake lever 50. A horizontally oriented cam 54 issecurely attached to the brake lever 50 and has a cam nose 56 and agenerally flat cam contact face 58. For example, as shown, the cam 54may be welded to a middle portion of the brake lever 50. As shown, thebrake lever 50 may be a curved bar having a circular cross-section andtwo opposed ends spanning across a horizontal plane. The brake lever 50thus provides a structure that allows an operator to effectivelymanipulate the brake lever 50 with his or her foot or hand. Although acurved bar having a circular cross-section is shown, the brake lever 50may have any other suitable shape, cross-section, or curvature.

The cam 54 is rotatably coupled with the upper mounting plate 40 suchthat the brake lever 50 and cam 54 are rotatable in a horizontal planeabout a vertical axis AA, as best seen in FIG. 3. The brake lever 50thus avoids interfering with the upper mounting plate 40, adjacentsurfaces of the transport vehicle, or the ground surface when the caster22 includes a caster wheel 36 having a small diameter. Specifically, asshown, the cam 54 is provided with a vertical through-hole 55 that iscoaxially aligned with a corresponding through-hole 61 on a tab 60 ofthe upper mounting plate 40. A shoulder screw 62 may be insertedupwardly through the through-holes 55, 61 respectively and be fittedwith a nut 64 at an opposing face of the tab 60 for coupling the cam 54with the upper mounting plate 40. The brake lever 50 and cam 54 arethereby rotatable about the vertical axis AA defined by the shoulderscrew 62. The shoulder screw 62 preferably includes a washer 66 forreducing friction and facilitating rotational movement, the washer 66being positioned between an upper surface of the cam 54 and a lowersurface of the upper mounting plate 40. Alternatively, the cam 54 may becoupled with the upper mounting plate 40 by a clevis pin, a rivet, orany other suitable mechanical fastener that all allows for rotationalmovement of the cam 54 while providing a strong mechanical coupling.

While the actuator of the braking system 20 is shown and describedherein as including the brake lever 50 and cam 54, the actuator mayinclude any other suitable pneumatic, hydraulic, or electrical deviceprovided in lieu of or in combination with the brake lever 50 and cam54.

A movable plunger 70 is disposed between the upper mounting plate 40 andthe caster plate 24, and is in operable engagement with and horizontallymovable by the cam 54. The movable plunger 70 is slidable through aspacer slot 43 in the spacer 42 toward and away from the central axis A.As best shown in FIG. 3, the movable plunger 70 is substantiallyT-shaped and includes a plunger contact face 72 formed integrally andsubstantially perpendicularly with a plunger arm 74. The plunger contactface 72 operates to follow the cam 54 and is configured to abut andreceive a horizontal compression force that is transferred from the camnose 56 and the cam contact face 58 upon movement of the cam 54. In thismanner, rotational movement of the cam 54 causes horizontaltranslational movement of the movable plunger 70. The plunger arm 74includes a horizontal through-hole 75 that is sized to receive a clevispin 76 with a slip fit such that the clevis pin 76 may easily rotatewithin the through-hole 75. The clevis pin 76 may include a groove ateach of its opposed ends for receiving a retaining clip 78.

The spacer 42 has a generally annular shape and includes a spacer slot43 that extends through a radial thickness of the spacer 42 and is sizedand shaped to slidably receive the plunger arm 74 therethrough. Thus,the plunger arm 74 is slidable toward and away from the central axis Ain a radial direction through the spacer slot 43. Material may beremoved from an outer surface 44 of the spacer 42 to form a flat face 45that is positioned radially inward of a plane (not shown) tangent to theouter surface 44. The flat face 45 thus permits the movable plunger 70to translate radially inward toward the central axis A withoutinterfering with the outer surface 44 of the spacer 42.

An adapter 80 is movably coupled with the movable plunger 70, by theclevis pin 76, and is vertically oriented within a bushing 90. Thebushing 90 is generally cylindrical and is positioned within a centralaperture 94 that extends vertically through the caster 22 along thecentral axis A. Specifically, the central aperture 94 extends verticallythrough the caster plate 24 and the horn base 28, and may include acounterbore 96 at the top surface of the caster plate 24 for receiving abushing flange 92.

The adapter 80 includes two parallel guides 82 that extend verticallyupward from an adapter base 84 and are spaced apart to define an adapterchannel 86 for receiving the plunger arm 74. Each guide 82 includes anangled slot 88 that is angled relative to a horizontal plane defined bythe caster plate 24, for example, and sized to receive the clevis pin 76therethrough. During assembly, the plunger arm 74 is inserted into thechannel 86 so that the horizontal through-hole 75 provided in theplunger arm 74 is aligned with the pair of angled slots 88 on theadapter 80. The clevis pin 76 is then inserted through the two guides 82and the plunger arm 74 positioned therebetween, and is retained in placewith the retaining clips 78.

The angled slots 88, and the clevis pin 76 acting therewith, areconfigured to convert a horizontal force to a vertical force, and thushorizontal movement to vertical movement. Specifically, the cam 54exerts a horizontal compression force on the movable plunger 70, whichin turn exerts a horizontal compression force on the adapter 80 throughthe clevis pin 76. The angled slots 88 on the adapter 80 receive thishorizontal compression force from the clevis pin 76 and convert it to avertical compression force. This vertical compression force causes theadapter 80, and a brake shoe 100 coupled therewith, to move verticallydownward along the central axis A through the bushing 90. The brake shoe100 thereby exerts a downward braking force on the caster wheel 36, asdescribed in greater detail below. In this manner, rotational movementof the cam 54 causes horizontal translational movement of the movableplunger 70 and clevis pin 76, which in turn causes verticaltranslational movement of the adapter 80 and brake shoe 100.

The angled slots 88 are formed with a slot angle defined by a centerline (not shown) along a length of each slot 88, measured relative to ahorizontal plane. This slot angle defines a horizontal-to-verticalstroke ratio corresponding to the horizontal movement of the movableplunger 70 and clevis pin 76 and the vertical movement of the adapter80. The angled slots 88 may be formed with a slot angle to provide ahorizontal-to-vertical stroke ratio of 2:1, for example. Furthermore,the slot angle directly affects the magnitude of the downward brakingforce exerted by the brake shoe 100 on the caster wheel 36. Forreference, one may consider the braking force exerted by the brake shoe100 when the angled slots 88 are formed with a slot angle of forty-fivedegrees. When the angled slots 88 are formed with a steeper slot angle,for example one greater than forty-five degrees but less than ninetydegrees, the downward braking force exerted on the wheel 36 decreases.Similarly, when the angled slots 88 are formed with a shallower slotangle, for example one less than forty-five degrees but greater thanzero degrees, the downward braking force exerted on the wheel 36increases. In this manner, the angled slots 88 may be formed with anysuitable slot angle to provide a desired downward braking force.

The brake shoe 100 is coupled with the adapter 80 and includes agenerally cylindrical shaft portion 102 oriented vertically along thecentral axis A, and a toe 104 extending downwardly from the shaftportion 102. The toe 104 is positioned external to the bushing 90 andadjacent to the caster wheel 36, and may be shaped to generally conformto the outer circumference of the caster wheel 36. For example, as shownin FIGS. 3 and 4A, the brake shoe toe 104 is a disk having a generallytruncated conical face. The shaft portion 102 is positioned within thebushing 90 and has a threaded bore 106 that is sized to receive athreaded stud 108 extending downwardly from a lower surface of theadapter base 84. The brake shoe 100 is thus threadedly engaged with theadapter 80 such that a vertical distance between the brake shoe toe 104and the adapter base 84 is adjustable by rotating the brake shoe 100 ina clockwise or counter-clockwise direction. Adjusting this verticaldistance will, in effect, also adjust a vertical distance between thebrake shoe 100 and other components of the braking system 20, such asthe movable plunger 70, for example. Vertical adjustment of the brakeshoe 100 is preferably performed when the brake shoe 100 is in aretracted, non-braking position, described below.

The brake shoe 100 is vertically movable along the central axis Abetween a retracted, non-braking position shown in FIG. 4A, and anextended, braking position shown in FIG. 5A. In the retracted,non-braking position, the brake shoe toe 104 is spaced apart from thecaster wheel 36 such that the wheel 36 is permitted to rotate about thewheel axle 34. In the extended, braking position, the brake shoe toe 104is in direct contact with the caster wheel 36 and exerts a verticalcompression braking force on the wheel 36 to completely block or atleast partially hinder rotation of the wheel 36.

The brake shoe 100 may be composed of any material or materials suitablefor the application and the environment in which the caster 22 isoperated. Suitable materials may include any metal or polymer of varyinghardness, including plastics, polyurethanes, and rubbers. For example,the brake shoe 100 may be formed of a metal and may include a polymercoating. The material or materials forming the brake shoe 100 may beselected based at least in part on the material or materials forming thecaster wheel 36. For example, the brake shoe 100 may be formed of ametal and the caster wheel 36 may be formed of a polymer or of a metalhaving a polymer coating in the form of a wheel tread. By way of furtherexample, the caster wheel 36 may be formed of metal and the brake shoe100 may be formed of a polymer or a metal having a polymer coating.

As shown in FIGS. 4A and 5A, a spring 112, shown as a compressionspring, is positioned within the bushing 90 and surrounds a portion ofthe length of the shaft portion 102 of the brake shoe 100. The spring112 includes an upper spring end 114 that is positioned adjacent to alower surface of the adapter base 84, and a lower spring end 116 that ispositioned adjacent to an internal base surface 93 of the bushing 90.The brake shoe 100 of the braking system 20 is thereby biased toward theretracted, non-braking position.

FIGS. 4 through 5A show additional detail of the braking system 20 whenthe brake lever 50 is rotated between first and second brake leverpositions to move the brake shoe 100 between the retracted, non-brakingposition and the extended, braking position.

FIGS. 4 and 4A show respectively a top elevational view, with the uppermounting plate 40 hidden, and a corresponding side cross-sectional viewof the braking system 20 in which the brake lever 50 in the first brakelever position. The cam 54 exerts no horizontal force on the movableplunger 70 sufficient to cause inward horizontal movement of the movableplunger 70. In turn, the movable plunger 70 exerts no horizontal force,through the clevis pin 76, on the angled slots 88 of the adapter 80sufficient to cause downward vertical movement of the adapter 80. Inturn, the adapter 80 exerts no vertical force on the brake shoe 100sufficient to cause downward vertical movement of the brake shoe 100.The spring 112 biases the adapter 80 vertically upward, and the brakeshoe 100 coupled with the adapter 80 is thus held in the retracted,non-braking position when the brake lever 50 is in the first brake leverposition.

FIGS. 5 and 5A show respectively a top elevational view, with the uppermounting plate 40 removed, and a corresponding side cross-sectional viewof the braking system 20 in which the brake lever 50 is rotated to asecond brake lever position. During rotation of the brake lever 50 fromthe first brake lever position, shown in FIGS. 4 and 4A, toward thesecond brake lever position, shown in FIGS. 5 and 5A, the cam nose 56first engages and exerts a horizontal force on the plunger contact face72. As the brake lever 50 is rotated further toward the second brakelever position, the cam contact face 58 next engages and exerts ahorizontal force on the plunger contact face 72. The cam contact face 58and plunger contact face 72 may have complimentary shapes such that thecontact faces 58, 72 remain engaged with each other once the brake lever50 has been fully moved to the second brake lever position. The brakelever 50 is thereby held in the second brake lever position, and thebrake shoe 100 is held in the extended, braking position, until thebrake lever 50 is rotated back toward the first brake lever position.For example, as shown, the contact faces 58, 72 may have mating surfacesthat are generally flat and parallel to one another.

As the brake lever 50 is rotated toward the second brake lever position,the cam 54 exerts a horizontal compression force on the movable plunger70 sufficient to cause the movable plunger 70 to translate horizontallyinward toward the central axis A. In turn, the movable plunger 70 exertsa horizontal compression force, through the clevis pin 76, on the angledslots 88 of the adapter 80. The angled slots 88 convert this horizontalcompression force to a vertical compression force sufficient to causethe adapter 80 to translate vertically downward along the central axis Aand compress the spring 112. In turn, the adapter 80 exerts a verticalcompression force on the brake shoe 100 sufficient to cause the brakeshoe 100 to translate vertically downward toward the extended, brakingposition. As permitted by the interaction between the cam contact face58 and plunger contact face 72, described above, the brake shoe 100 ofthe braking system 20 preferably remains in the extended, brakingposition until the brake lever 50 is rotated back toward the first brakelever position.

FIGS. 6 through 7A show another embodiment of the invention in which thebraking system 20, as described above, further includes a swivel lock120. The swivel lock 120 operates to fix the caster horn 26 in a desiredrotational position relative to the caster plate 24, and thereby preventthe horn 26 and the caster wheel 36 from swiveling. In essence, thecaster 22 is non-permanently converted from a swivel caster to a rigidcaster for straight line steering control of the transport vehicle towhich the caster 22 is mounted. The swivel lock 120 preferablyincorporates a structural design that does not interfere with the brakelever 50 or with any other actuator design described herein.

As shown in FIGS. 6 and 6A, the swivel lock 120 includes a horizontallyoriented lock lever 122 that is in operable engagement with andconfigured to move a movable plunger 130. The lock lever 122 is attachedto and may be formed integrally with a lock cam 124. The lock cam 124includes a pair of cam plates 125 extending horizontally from the locklever 122, each cam plate 125 having a nose 126 and a cam contact face128. The cam plates 125 are spaced vertically to define a cam channel129 therebetween that is sized to receive a shaft portion 132 of themovable plunger 130. The lock cam 124 is rotatably coupled with themovable plunger 130 by a pin 136, such that the lock cam 124 isrotatable about a vertical axis defined by the pin 136.

The swivel lock 120 further includes a housing 140 having a central borefor slidably receiving the movable plunger 130, and two notches 142 forsupporting the cam plates 125. The movable plunger 130 is slidablewithin the housing 140 along a horizontal plane and includes a shaftportion 132 and a locking tip 134 extending from the shaft portion 132.The movable plunger 130 may be generally cylindrical in shape and theshaft portion 132 may have a smaller diameter than the locking tip 134.A spring 144, shown as a compression spring, is positioned within thehousing 140 and surrounds the shaft portion 132 such that the spring 144abuts the locking tip 134 at one end and an internal surface of thehousing 140 at the other end.

The swivel lock 120 is mounted to the caster plate 24 such that thelocking tip 134 is positioned adjacent to the horn base 28. The hornbase 28 includes one or more locking slots 150 spaced about thecircumference of the horn base 28 to define various positions in whichthe horn 26 may be locked to prevent swiveling. For example, as shown,the horn base 28 includes four locking slots 150 spaced at ninety degreeintervals about the central axis A, thereby defining four orientationsin which the horn 26 maybe locked to prevent swiveling. Each lockingslot 150 is sized and shaped to receive the locking tip 134 of themovable plunger 130. For example, as shown, the locking tip 134 is of agenerally cylindrical shape and the locking slots 150 are generallyrectangular and extend vertically to define a width corresponding to thediameter of the locking tip 134.

As shown by FIGS. 6 through 7A, the movable plunger 130 is movable bythe lock cam 124 and lock lever 122 between an extended, locked positionin which the horn 26 and caster wheel 36 are prevented from swiveling,and a retracted, unlocked position in which swiveling is enabled. Thespring 144 biases the movable plunger 130 toward the extended, lockedposition.

FIGS. 6 and 6A show respectively an isometric view and a correspondingtop cross-sectional view of the caster 22 in which the lock lever 122 isin the first lock lever position. The lock cam 124 exerts no horizontalforce on the movable plunger 130 sufficient to cause outward horizontalmovement of the movable plunger 130. A spring force provided by thespring 144 holds the movable plunger 130 in the extended, lockedposition in which the locking tip 134 engages and exerts a horizontalcompression force on the locking slot 150 to thereby prevent the horn 26from swiveling when the lock lever 122 is in the first lock leverposition.

FIGS. 7 and 7A show views similar to FIGS. 6 and 6A, but when the locklever 122 is moved to the second lock lever position. As the lock lever122 is rotated from the first lock lever position toward the second locklever position, the lock cam 124 rotates about the pin 136 such that thecam nose 126 of each cam plate 125 first engages and exerts a horizontalcompression force on the corresponding notch 142 of the swivel lockhousing 140. As the lock lever 122 is rotated further toward the secondlock lever position, the cam contact face 128 of each cam plate 125 nextengages and exerts a horizontal compression force on the correspondingnotch 142. Simultaneously, the lock cam 124 exerts a horizontal tensionforce on the movable plunger 130 through the pin 136. The movableplunger 130 is thereby drawn horizontally outward toward the retracted,unlocked position in which the spring 144 is compressed and the lockingtip 134 is disengaged from the locking slot 150. Swiveling of the horn26 and caster wheel 36 is thereby enabled. The cam contact faces 128 andnotches 142 may have complimentary shapes such that the contact faces128 and notches 142 remain engaged with each other once the lock lever122 has been fully moved to the second lock lever position. The locklever 122 is thereby held in the second lock lever position, and themovable plunger 130 is held in the retracted, unlocked position, untilthe lock lever 122 is rotated back toward the first lock lever position.For example, as shown, the cam contact faces 128 and notches 142 mayhave mating surfaces that are generally flat and parallel to oneanother.

Referring to FIGS. 8 through 12A, another embodiment of the invention isshown in which a braking system 220 provides a “dead man” type brake inwhich the brake shoe 100 remains in the extended, braking positionunless and until an operator applies and continuously maintains atension force on the braking system 220 to move the brake shoe 100toward the retracted, non-braking position. The braking system 220includes the same components as those comprising braking system 20,except as distinguished below.

As shown particularly in FIGS. 8 through 10, the actuator of brakingsystem 220 includes a control cable 230 and a hand lever 240 forexerting a tension force on the control cable 230. As better shown inFIGS. 11A and 12A, the control cable 230 is preferably housed within aprotective sheath 232 and includes a threaded end 234 that is insertedinto and threadedly engaged with a threaded hole 236 provided on theplunger contact face 72. The threaded end 234 may be provided with aretaining nut 238 for tightening or loosening the engagement of thethreaded end 234 with the threaded hole 236. The coupling of the controlcable 230 with the movable plunger 70 enables the control cable 230 toexert a tension force on the movable plunger 70 in a horizontaldirection away from the central axis A.

As shown in FIGS. 10, 11A, and 12A, the braking system 220 includes abushing 250 and a spring 260 of a different structure and placement thanthe corresponding elements of the braking system 20, in order to providethe dead man type braking function. The bushing 250 includes an upperinternal base surface 252 and a lower internal base surface 254, eachbeing disposed between the two opposed ends of the bushing 250. Thespring 260, shown as a compression spring, is positioned only partlywithin the bushing 250 and surrounds a portion of the length of theshaft portion 102 of the brake shoe 100. The spring 260 has an upperspring end 262 that is positioned adjacent to the lower internal basesurface 254 of the bushing 250, and a lower spring end 264 that ispositioned adjacent to the toe 104 of the brake shoe 100.

Referring back to FIG. 8, the hand lever 240 is mounted to the transportvehicle, shown as platform truck or cart 10, at a location at which itis easily reached and manipulated by the hand of an operator. Forexample, as shown, the hand lever 240 is rotatably coupled with a perch242 that is mounted to an upper portion of the transport bar 18. Thecontrol cable 230 is coupled with the hand lever 240 such that rotatingthe hand lever 240 toward a second hand lever position, for example bysqueezing the hand lever 240, results in the exertion of a tension forceby the hand lever 240 on the control cable 230. As shown, the controlcable 230 has a sufficient length for routing from the location of thehand lever 240 to the location of the movable plunger 70. To prevent anyexcessive length of the control cable 230 from interfering with use ofthe transport vehicle, the control cable 230 may be secured to thevehicle by any suitable means. For example, as shown, strap elements 244may be wrapped or otherwise positioned around the protective sheath 232and a portion of the transport bar 18 at various positions along thelength of the control cable 230. Additionally, as shown in FIG. 8, thetransport vehicle may be provided with multiple braking systems 220,wherein each braking system 220 may share a common hand lever 240.

FIGS. 11 through 12A show additional detail of the braking system 220when the hand lever 240 is rotated or otherwise manipulated betweenfirst and second hand lever positions to actuate the control cable 230between first and second cable positions and thereby move the brake shoe100 between the extended, braking position and the retracted,non-braking position. As discussed above, the braking system 220operates as a dead man type brake. Specifically, the brake shoe 100remains in the extended, braking position, under the spring forceprovided by spring 260, unless and until an operator applies andcontinuously maintains a tension force on the control cable 230 to movethe brake shoe 100 toward the retracted, non-braking position. Uponrelease of the tension force, the brake shoe 100 moves back to theextended, braking position.

FIGS. 11 and 11A show respectively a top elevational view, with theupper mounting plate 40 hidden, and a corresponding side cross-sectionalview of the braking system 220 in which the control cable 230 is in thefirst cable position when the hand lever 240 is in the first hand leverposition. The hand lever 240 in the first hand lever position is in aneutral state and not being manipulated by an operator, and thus exertsno tension force on the control cable 230. In turn, the control cable230 exerts no horizontal force on the movable plunger 70 sufficient tocause outward horizontal movement of the movable plunger 70. In turn,the movable plunger 70 exerts no horizontal force, through the clevispin 76, on the angled slots 88 of the adapter 80 sufficient to causeupward vertical movement of the adapter 80. In turn, the adapter 80exerts no vertical force on the brake shoe 100 sufficient to causeupward vertical movement of the brake shoe 100. The spring 260 biasesthe brake shoe 100 vertically downward, and the brake shoe 100 is thusheld in the extended, braking position in engagement with the wheel 36when the control cable 230 and hand lever 240 are in the first cableposition and the first hand lever position, respectively.

FIGS. 12 and 12A show respectively a top elevational view, with theupper mounting plate 40 hidden, and a corresponding side cross-sectionalview of the braking system 220 in which the control cable 230 is in thesecond cable position when the hand lever 240 is in the second handlever position. The hand lever 240 may be moved into the second handlever position by an operator who squeezes or otherwise manipulates thehand lever 240. As the hand lever 240 is moved toward the second handlever position, the hand lever 240 exerts a tension force on the controlcable 230 sufficient to cause the control cable 230 to move in adirection toward the hand lever 240. If the protective sheath 232 hasbeen fixed to the transport vehicle such that it is prevented frommoving with the control cable 230, the protective sheath 232 will remainstationary as the control cable 230 slides within the protective sheath232. In turn, the control cable 230 exerts a horizontal tension force onthe movable plunger 70 sufficient to cause the movable plunger 70 totranslate horizontally outward from the central axis A. In turn, themovable plunger 70 exerts a horizontal tension force, through the clevispin 76, on the angled slots 88 of the adapter 80. The angled slots 88convert this horizontal tension force to a vertical tension forcesufficient to cause the adapter 80 to translate vertically upward alongthe central axis A. In turn, the adapter 80 exerts a vertical tensionforce on the brake shoe 100 sufficient to cause the brake shoe 100 totranslate vertically upward toward the retracted, non-braking positionin which the toe 104 of the brake shoe 100 does not contact the casterwheel 36. In turn, the brake shoe 100 compresses the spring 260, whichthereby operates to bias the brake shoe 100 back toward the extended,braking position. Accordingly, when the operator ceases to hold the handlever 240 in the second hand lever position, a tension force is nolonger applied to the control cable 230 and the spring force exerted bythe spring 260 causes the brake shoe 100 to return to the extended,braking position to completely block or at least partially hinderrotation of the caster wheel 36.

As used herein, the terms “vertical” and “horizontal” and variationsthereof are to be understood with reference to the structure of thecaster 22, as shown. Specifically, the term “vertical” refers to adirection that is parallel with the vertically oriented central axis Aof the caster 22. The term “horizontal” refers to a direction that istransverse to the central axis A and, for example, parallel to thecaster plate 24.

Similarly, as used herein, the terms “upward” and “downward” andvariations thereof are to be understood with reference to the verticallyoriented central axis A and the caster 22. Specifically, the term“upward” refers to movement that is parallel to the central axis A andin a direction from the caster wheel 36 toward the caster plate 24. Theterm “downward” also refers to movement that is parallel to the centralaxis A but in a direction from the caster plate 24 toward the casterwheel 36.

Similarly, as used herein, the terms “inward” and “outward” andvariations thereof are also to be understood with reference to thevertically oriented central axis A. Specifically, the term “inward”refers to movement that is transverse to and in a radial directiontoward the central axis A. The term “outward” refers to movement that istransverse to and in a radial direction away from the central axis A.

Accordingly, persons skilled in the art will appreciate that the terms“vertical,” “horizontal,” “upward,” “downward,” “inward,” or “outward,”and their variations as used herein, may adopt different meanings withrespect to a ground surface depending on the orientation in which thecaster 22 is mounted to a transport vehicle.

While the present invention has been illustrated by the description ofspecific embodiments thereof, and while the embodiments have beendescribed in considerable detail, it is not intended to restrict or inany way limit the scope of the appended claims to such detail. Thevarious features discussed herein may be used alone or in anycombination. Additional advantages and modifications will readily appearto those skilled in the art. The invention in its broader aspects istherefore not limited to the specific details, representative apparatusand methods and illustrative examples shown and described. Accordingly,departures may be made from such details without departing from thescope or spirit of the general inventive concept.

What is claimed is:
 1. A caster wheel braking system for brakingrotation of a caster wheel, comprising: a caster including a casterplate, a horn base coupled with the caster plate and rotatable about avertical axis, a pair of legs extending downwardly from the horn base,and at least one caster wheel coupled with the pair of legs androtatable about a horizontal axis defined by a caster wheel axle; amounting plate spaced from the caster by a spacer; a movable plungerdisposed between the caster plate and the mounting plate andhorizontally movable through a slot provided in the spacer; a brake shoevertically movable by the movable plunger between a non-braking positionin which the at least one caster wheel is permitted to rotate and abraking position in which the brake shoe exerts a braking force on theat least one caster wheel to at least partially hinder rotation of theat least one caster wheel; and a pin coupled with the movable plungerand configured to convert horizontal movement of the movable plunger tovertical movement of the brake shoe.
 2. The braking system of claim 1,further comprising: an actuator configured to move the movable plungerto thereby cause movement of the brake shoe between the non-braking andbraking positions.
 3. The braking system of claim 2, wherein theactuator is coupled with the mounting plate.
 4. The braking system ofclaim 2, wherein the actuator includes a brake lever rotatable about avertical axis.
 5. The braking system of claim 4, wherein the actuatorfurther includes a cam attached to the brake lever and configured toconvert rotational movement of the brake lever into horizontaltranslational movement of the movable plunger.
 6. The braking system ofclaim 5, wherein the movable plunger is substantially T-shaped.
 7. Thebraking system of claim 2, wherein the actuator includes a control cableand the brake shoe is moveable toward the non-braking position when atension force is exerted on the control cable.
 8. The braking system ofclaim 7, wherein the actuator further includes a hand lever coupled withthe control cable, the hand lever is configured to exert the tensionforce on the control cable.
 9. The braking system of claim 1, wherein avertical distance between the brake shoe and the movable plunger isadjustable when the brake shoe is in the non-braking position.
 10. Thebraking system of claim 1, wherein at least a portion of the at leastone caster wheel is composed of a polymer and at least a portion of thebrake shoe is composed of a metal.
 11. The braking system of claim 10,wherein at least a portion of the at least one caster wheel is composedof a plastic material.
 12. The braking system of claim 10, wherein atleast a portion of the at least one caster wheel is composed of apolyurethane material.
 13. The braking system of claim 10, wherein atleast a portion of the brake shoe is composed of a polymer.
 14. Thebraking system of claim 1, wherein at least a portion of the at leastone caster wheel is composed of a metal and at least a portion of thebrake shoe is composed of a polymer.
 15. The braking system of claim 1,wherein the at least one caster wheel includes two caster wheels.
 16. Acaster wheel braking system for braking rotation of a caster wheel,comprising: a caster including a caster plate, a horn base coupled withthe caster plate and rotatable about a vertical axis, a pair of legsextending downwardly from the horn base, and at least one caster wheelcoupled with the pair of legs and rotatable about a horizontal axisdefined by a caster wheel axle; a mounting plate spaced from the casterby a spacer; a movable plunger disposed between the caster plate and themounting plate and horizontally movable through a slot provided in thespacer; a brake shoe vertically movable by the movable plunger between anon-braking position in which the at least one caster wheel is permittedto rotate and a braking position in which the brake shoe exerts abraking force on the at least one caster wheel to at least partiallyhinder rotation of the at least one caster wheel; and a biasing elementadjacent to the brake shoe and configured to bias the brake shoe towardthe non-braking position or the braking position.
 16. The braking systemof claim 15, further comprising: an actuator configured to move themovable plunger to thereby cause movement of the brake shoe between thenon-braking and braking positions.
 17. The braking system of claim 16,wherein the actuator is coupled with the mounting plate.
 18. The brakingsystem of claim 16, wherein the actuator includes a brake leverrotatable about a vertical axis and the biasing element is configured tobias the brake shoe toward the non-braking position.
 19. The brakingsystem of claim 16, wherein the actuator includes a control cableconfigured to cause movement of the brake shoe toward the non-brakingposition when a tension force is exerted on the control cable, and thebiasing element is configured to bias the brake shoe toward the brakingposition.
 20. A transport vehicle configured to move along a groundsurface and including at least one caster wheel braking system forbraking rotation of a caster wheel, the at least one caster wheelbraking system comprising: a caster coupled with the transport vehicle,the caster including a caster plate, a horn base coupled with the casterplate and rotatable about a vertical axis, a pair of legs extendingdownwardly from the horn base, and at least one caster wheel coupledwith the pair of legs and rotatable about a horizontal axis defined by acaster wheel axle; a mounting plate spaced from the caster by a spacer;a movable plunger disposed between the caster plate and the mountingplate and horizontally movable through a slot provided in the spacer; abrake shoe vertically movable by the movable plunger between anon-braking position in which the at least one caster wheel is permittedto rotate and a braking position in which the brake shoe exerts abraking force on the at least one caster wheel to at least partiallyhinder rotation of the at least one caster wheel; and a pin coupled withthe movable plunger and configured to convert horizontal movement of theplunger to vertical movement of the brake shoe.
 21. The transportvehicle of claim 20, further comprising: a brake lever rotatable about avertical axis and configured to move the movable plunger to therebycause movement of the brake shoe between the non-braking and brakingpositions.
 22. The transport vehicle of claim 20, further comprising: acontrol cable coupled with the movable plunger, wherein the brake shoeis moveable by the control cable toward the non-braking position when atension force is exerted on the control cable.
 23. The transport vehicleof claim 20, wherein the at least one caster wheel braking systemincludes at least two of the caster wheel braking systems.